The invention relates to a feed block unit for a hot-runner feed system of a pressure die-casting machine, wherein the feed block unit includes a block body in which there is incorporated at least one melt-conveying channel running out of the block body by way of a sprue orifice close to the gate, and a heating system, integrated into the block body, for the at least one melt-conveying channel. Furthermore, the invention relates to a hot-runner feed system and to a control device for such a pressure die-casting machine.
EP patent 1 201 335 B1 discloses a hot-runner feed system of the above-mentioned type, which is designed, for example, as a comb-type or fan-type feed system. In such a system, a feed part, which is a non-detachable component of a fixed mould half, contains a plurality of nozzles or feed elements in a distributed arrangement, each comprising a central supply channel and a nozzle tip with one or more sprue channels which adjoin the supply channel and have a smaller channel cross section in relation thereto. The sprue channels each terminate in a sprue orifice close to the gate. This means that the sprue orifice in question directly forms the so-called gate or is situated immediately in front of this gate region. The gate or gate region refers to that point at which the cast shape breaks away from the residual sprue of the melt, i.e., the gate forms the predetermined breaking point for the cast shape of solidified melt in the adjoining sprue region. This means that the sprue orifice in this feed system is situated directly at the edge of the mould cavity or immediately in front of it. The melt is fed into the nozzle supply channels from a feed mouthpiece, which is formed at the inlet side of the feed part, via distributing runner channels in the feed part. The runner channels can be heated, and in addition each nozzle is assigned its own heating element in the form of an electric heating element, which surrounds the cylindrical nozzle body.
The technical problem underlying the invention is that of providing a feed block unit of the above-mentioned type, together with a hot-runner feed system and a control device for a pressure die-casting machine, whereby the flexibility of the feed system of pressure die-casting machines, the heating of the melt in the feed system, and/or the control of the pressure die-casting machine can be improved in relation to the prior art.
The feed block unit according to the invention is designed as a structural unit which can be inserted independently into a respective casting mould and which includes a block body, in which at least one melt-conveying channel is incorporated, and a heating system integrated into the block body. In other words, the feed block unit is not a fixed, non-detachable feed block part of a casting mould or mould half, but instead may be used in a modular and flexible fashion in various casting moulds which for this purpose are provided with corresponding mounting openings. It is also possible in this respect for a plurality of such feed block units to be used in any desired, arrangement configuration depending on the size and shape of the casting mould. The at least one melt-conveying channel runs out of the block body of the feed block unit by way of a sprue orifice close to the gate, which means that the feed block unit forms, or is mounted immediately upstream of, the gate region for the respective mould by way of this sprue orifice close to the gate. This, in turn, means that by using this feed block unit the melt can be actively heated over its feedpath right up until it reaches the mould cavity.
In the feed block unit according to the invention, the at least one melt-conveying channel includes at least one supply channel and at least one sprue channel leading therefrom to the associated sprue orifice close to the gate, and the heating system integrated into the block body of the feed block unit includes at least a first controllable heating device for supply channel heating and a second heating device, which can be controlled independently of the first heating device, for sprue channel heating. The thus possible independent active heating of the supply channel, on the one hand, and the sprue channel, on the other hand, allows comparatively variable temperature profiles to be set for the path followed by the melt in the feed block unit. As a result, it is possible for the temperature profile for the path of the melt in the feed block unit, from the supply channel inlet to the sprue orifice close to the gate, to be adapted variably to the respective application and in this way to be optimized.
In one embodiment of this aspect of the invention, the first and/or the second heating device includes a plurality of electric heating circuits. Consequently, the supply channel heating and/or the sprue channel heating can be further optimized in corresponding applications. If required, it is possible for the plurality of electric heating circuits for supply channel heating and/or sprue channel heating to be controlled separately, thereby further improving the heating of the melt on its path through the feed block unit.
In one development of the feed block unit according to the invention, the at least one supply channel extends in an axial direction, and the at least one sprue channel leads transversely away from the supply channel. It is therefore possible in this feed block unit for melt to be fed in axially and then to be introduced into the mould cavity in the transverse direction.
The hot-runner feed system is equipped with one or more feed block units according to the invention and with a manifold block structure on which the one or more feed block units are mounted on a feed side. The manifold block structure is provided with one or more runner channels via which melt can be fed into the melt-conveying channel or channels of the one or more feed block units. In this way, the manifold block structure, together with the feed block unit or units mounted thereon, forms a modular structural unit which can be used variably and which can be variously configured depending on the particular application and inserted into a mould or mould half. In order, for example, to achieve a comb-type hot-runner feed system, a plurality of feed block units can be arranged in a linear, i.e. one-dimensional, configuration or in a two-dimensionally distributed configuration on the manifold block structure and inserted thus into a mould or mould half at distributed points on a feed side.
In one development of the invention, the manifold block structure includes one or more manifold block elements, wherein the respective manifold block element can be actively heated. This ensures a continuously heated distribution of melt, which is fed into the manifold block structure via, for example, an upstream metering unit including a casting plunger and nozzle, to the individual feed block units coupled to the manifold block structure.
The hot-runner feed system includes at least one feed block unit and at least one heating control circuit for the controlled heating thereof, wherein the heating control circuit includes at least two heating elements for the respective feed block unit, which can be controlled individually to set a predeterminable temperature profile. In operation this allows a comparatively variable and precise setting of the temperature for the melt flowing through the feed block unit before the melt passes from there directly into the mould cavity. It will be understood that, if required, further individually controlled heating elements can be provided along the melt flow path situated upstream of the feed block unit.
The control device is intended for controlling a pressure die-casting machine which serves for the production of metal die-cast parts and which includes a hot-runner feed system together with feed system temperature sensors, wherein, in particular, the hot-runner feed system can be a hot-runner feed system according to the invention. The control device is configured to control a respective mould-filling operation dependent on temperature information supplied to it by the feed system temperature sensors. As a result, the mould-filling operation, i.e. the filling of the mould cavity with the melt, can be made dependent on the detected temperature of the melt in the feed system part.
In one development of the invention, this is used to authorize or to start the respective mould-filling operation only when one or more temperatures in the hot-runner feed system detected by the feed system temperature sensors lie within a respectively predetermined setpoint temperature range or setpoint temperature window. It is thus ensured that the mould is cast only when predetermined desired temperature conditions exist in the feed system, for example in one or more feed block units according to the invention used in the hot-runner feed system.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description when considered in conjunction with the accompanying drawings.